JP7422674B2 - Rubber compositions, tread rubber and tires - Google Patents

Description

Cross-reference of related applications

This application claims the benefit of priority of Japanese Patent Application No. 2018-189549 filed on October 4, 2018, the contents of which are incorporated into this application by reference.

TECHNICAL FIELD The present invention relates to rubber compositions, tread rubber and tires.

Conventionally, grip performance on wet road surfaces (hereinafter referred to as "wet performance") has been improved using inorganic fillers such as silica. However, such fillers also increase energy loss, making it difficult to reduce rolling resistance.

Furthermore, tires are required not only to have abrasion resistance against wear over time due to running, but also to have breakage resistance against chipping of the tire rubber when running on rough roads.

For example, Patent Document 1 provides a rubber composition for a tire tread that is suitable for use in manufacturing a tire that has an excellent balance between wet grip performance and low rolling resistance performance without impairing the wear resistance of the tire. Therefore, in the temperature dispersion curve of tan δ as a rubber component, the peak temperature of tan δ on the high temperature side is between -10°C and -50°C, and the peak temperature of tan δ on the low temperature side is lower than the peak on the high temperature side. The compound contains at least two types of diene rubber that are bimodal and have a lower temperature of 10°C or more, and further contains at least one reinforcing filler in a total of 30 to 90 parts by weight per 100 parts by weight of rubber, and the bond of the compound We have proposed a rubber composition for tire treads in which the content of the high Tg rubber component in the rubber is [compounding ratio of the high Tg rubber component] x 0.7 or less. However, in this case, it was not easy to achieve both low rolling resistance and wear resistance.

Publication No. 8-27313

Therefore, an object of the present invention is to provide a rubber composition that has a high balance of wet performance, abrasion resistance, low rolling resistance, and fracture resistance. Another object of the present invention is to provide a tread rubber and a tire that have a high balance of wet performance, abrasion resistance, low rolling resistance, and fracture resistance.

The rubber composition according to the present invention includes a rubber component and a filler,
The rubber component includes at least a modified conjugated diene polymer (A1), a modified conjugated diene polymer (A2), and a third polymer, which are different from each other,
The modified conjugated diene polymer (A1) has a weight average molecular weight of 20×10 ⁴ to 300×10 ⁴ , and has a molecular weight of 200×10 ⁴ with respect to the total weight of the modified conjugated diene polymer (A1). It contains 0.25 to 30% by mass of the modified conjugated diene polymer having a molecular weight of ~500×10 ⁴ , and has a shrinkage factor (g') of less than 0.64,
The rubber component is separated into at least two polymer phases, a polymer phase (1) having the highest peak temperature of the tan δ temperature dispersion curve and a polymer phase (2) having the lowest peak temperature,
The polymer phase (1) and the polymer phase (2) are mutually incompatible,
The polymer phase (1) includes at least the modified conjugated diene polymer (A1), the modified conjugated diene polymer (A2), and the filler,
When the proportion (%) of the filler in the polymer phase (1) is X, and the average aggregate area (nm ² ) of the filler in the polymer phase (1) is Y, X and Y are expressed by the following formula (1). :
Y<4.8X+1200 (1)
It is a rubber composition that satisfies the following.
This makes it possible to achieve a high balance between wet performance, wear resistance, low rolling resistance, and fracture resistance.

The tread rubber according to the present invention is a tread rubber using any of the rubber compositions described above.
Thereby, the wet performance, abrasion resistance, low rolling resistance, and fracture resistance of the tread rubber can be highly balanced.

A tire according to the present invention is a tire using any of the rubber compositions described above.
This makes it possible to highly balance the tire's wet performance, wear resistance, low rolling resistance, and fracture resistance.

According to the present invention, it is possible to provide a rubber composition that has a high balance of wet performance, abrasion resistance, low rolling resistance, and fracture resistance. According to the present invention, it is possible to provide a tread rubber and a tire that have a highly balanced wet performance, abrasion resistance, low rolling resistance, and fracture resistance.

Embodiments of the present invention will be described below. These descriptions are for the purpose of illustrating the invention and are not intended to limit the invention in any way.

In the following description, the modified conjugated diene polymer (A1) and the modified conjugated diene polymer (A2) may be referred to as component (A1) and component (A2), respectively.

As used herein, numerical ranges are intended to include the lower and upper limits of that range, unless otherwise specified. For example, 0.25 to 30% by mass means 0.25% by mass or more and 30% by mass or less.

(Rubber composition)
The rubber composition according to the present invention includes a rubber component and a filler,
The rubber component includes at least a modified conjugated diene polymer (A1), a modified conjugated diene polymer (A2), and a third polymer, which are different from each other,
The modified conjugated diene polymer (A1) has a weight average molecular weight of 20×10 ⁴ to 300×10 ⁴ , and has a molecular weight of 200×10 ⁴ with respect to the total weight of the modified conjugated diene polymer (A1). It contains 0.25 to 30% by mass of the modified conjugated diene polymer having a molecular weight of ~500×10 ⁴ , and has a shrinkage factor (g') of less than 0.64,
The rubber component is separated into at least two polymer phases, a polymer phase (1) having the highest peak temperature of the tan δ temperature dispersion curve and a polymer phase (2) having the lowest peak temperature,
The polymer phase (1) and the polymer phase (2) are mutually incompatible,
The polymer phase (1) includes at least the modified conjugated diene polymer (A1), the modified conjugated diene polymer (A2), and the filler,
When the proportion (%) of the filler in the polymer phase (1) is X, and the average aggregate area (nm ² ) of the filler in the polymer phase (1) is Y, X and Y are expressed by the following formula (1). :
Y<4.8X+1200 (1)
It is a rubber composition that satisfies the following.
This makes it possible to achieve a high balance between wet performance, wear resistance, low rolling resistance, and fracture resistance.

・Polymer phase The rubber component is separated into at least two polymer phases: a polymer phase (1) with the highest peak temperature in the tan δ temperature dispersion curve and a polymer phase (2) with the lowest peak temperature. ) and the polymer phase (2) are mutually incompatible. Furthermore, the polymer phase (1) includes at least a modified conjugated diene polymer (A1), a modified conjugated diene polymer (A2), and a filler. Further, when the filler proportion (%) in the polymer phase (1) is X and the average aggregate area (nm ² ) of the filler in the polymer phase (1) is Y, X and Y are expressed by the following formula (1):
Y<4.8X+1200 (1)
satisfy. That is, in equation (1), when X and Y are expressed in the above units, Y is smaller than 4.8X+1200 on the right side. When this formula (1) is satisfied, a larger amount of the filler in the rubber composition is distributed in the polymer phase (1), and the filler is more highly dispersed in the polymer phase (1). Therefore, wet performance, wear resistance, low rolling resistance, and fracture resistance can be highly balanced.

When there are only three types of rubber components: component (A1), component (A2), and third polymer, the polymer phase (1) is composed of component (A1), component (A2), and the like as described above. , a filler, and the polymer phase (2) includes a third polymer. In this case, the polymer phase (2) may or may not contain a filler.

In the present invention, the tan δ temperature dispersion curve of the polymer phase is obtained by measurement using a viscoelastic spectrometer manufactured by Toyo Seiki Co., Ltd. under the conditions of a strain of 1% and a frequency of 52 Hz.

In the present invention, it is confirmed using FIB-SEM that a polymer phase (1) and a polymer phase (2) exist and that these polymer phases are incompatible. Specifically, we used FIB-SEM to observe a 4 μm x 4 μm area of the rubber composition, and found that there was a difference in the degree of dyeing, indicating the presence of polymer phase (1) and polymer phase (2). Assume that the polymer phases of are incompatible. In this case, they may be compatible when observed with the naked eye.

In the present invention, the proportion of filler in the polymer phase (1) is determined by the following steps 1 to 4.
Procedure 1: Determine the amount (parts by mass) of the polymer present in the polymer phase (1). For example, when there are three types of rubber components: component (A1), component (A2), and a third polymer, the polymers present in the polymer phase (1) are component (A1) and component (A2). There are only two types. Therefore, in this case, the total parts by mass of component (A1) and component (A2) blended into the rubber composition is the amount (parts by mass) of the polymer present in the polymer phase (1).
Step 2: Find the proportion (distribution rate) of the filler distributed (present) in the polymer phase (1). The method for determining the filler distribution ratio will be described later.
Step 3: Calculate the value obtained by multiplying the amount of filler contained in the rubber composition by the distribution ratio of filler in the polymer phase (1). This value is the amount (parts by mass) of the filler distributed in the polymer phase (1).
Step 4: The amount of filler distributed (parts by mass) determined in Step 3 is divided by the amount (parts by mass) of the polymer present in the polymer phase (1) determined in Step 1, and multiplied by 100 to obtain a value. This value is the proportion (%) of filler in the polymer phase (1).

In step 2 above, the distribution ratio (%) of the filler distributed in the polymer phase (1) is the proportion (%) of the filler contained in the polymer phase (1) relative to the total area of fillers contained in all polymer phases of the rubber composition. Calculate as a percentage of the filler area. Specifically, it is determined by the following steps 2-1 to 2-4.
Procedure 2-1: Measure the smooth surface of the rubber composition sample cut with a microtome using AFM in a measurement range of 2 μm x 2 μm. The obtained AFM image is converted into a multivalued image (for example, a ternary image in the case of polymer phases (1) and (2)) of each polymer phase and filler using a histogram.
Step 2-2: Based on the multivalued image, determine the area of the filler contained in each polymer phase.
Step 2-3: Let the total area of the filler be the total area of the filler contained in all polymer phases.
Step 2-4: The ratio (%) of the area of the filler contained in the polymer phase (1) to the total area of the filler is defined as the distribution ratio (%) of the filler present in the polymer phase (1).
When the filler is located at the interface between the polymer phases, the area of the filler is divided by connecting two points where each polymer phase and the filler are in contact.

In the present invention, the average agglomerate area of the filler in the polymer phase (1) is determined by determining the agglomerate area of the filler portion of the polymer phase (1) from an image obtained in a measurement range of 4 μm x 4 μm using FIB-SEM. The average agglomerate area of the filler part is calculated by number average (arithmetic mean) from the total surface area of the part and the number of agglomerates. In the calculation, particles that are in contact with the edges (sides) of the image are not counted, and particles that are smaller than 20 pixels are regarded as noise and are not counted.

In formula (1), X is not particularly limited as long as it satisfies formula (1), and for example, X is 30 or more, 50 or more, 100 or more, 150 or more, or 200 or more. Further, for example, X is 350 or less, 300 or less, 250 or less, or 200 or less. The larger X is, the higher the proportion of filler in the polymer phase (1) is, and the wet performance is further improved. If X is less than 50, the effect of the present invention is small, so X is preferably 50 or more.

In the rubber composition according to the present invention, X in the formula (1) is preferably larger than 100.
This makes it possible to achieve a more advanced balance between low rolling resistance and wet performance.

In formula (1), Y is not particularly limited as long as it satisfies formula (1), and for example, Y is 2000 or less, 1950 or less, 1750 or less, or 1600 or less. Further, for example, Y is 1000 or more, 1200 or more, 1300 or more, 1400 or more, 1500 or more, or 1600 or more. The smaller Y is, the smaller the average aggregate area of the filler in the polymer phase (1) is, the more the filler is highly dispersed in the polymer phase (1), and the lower the rolling resistance is further improved.

<Rubber component>
The rubber composition according to the present invention includes at least a modified conjugated diene polymer (A1), a modified conjugated diene polymer (A2), and a third polymer, which are different from each other as rubber components.

Component (A1) and component (A2) are both modified conjugated diene polymers.

The conjugated diene polymer is a polymer of one type of conjugated diene compound or a copolymer of two or more types of conjugated diene compounds. Further, the conjugated diene polymer may be a copolymer of a conjugated diene compound and an aromatic vinyl compound.

Examples of the conjugated diene compound include 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, 2-phenyl-1,3-butadiene, 3-methyl-1, Examples include compounds having 4 to 12 carbon atoms such as 3-pentadiene, 1,3-hexadiene, and 1,3-heptadiene. As the conjugated diene compound, 1,3-butadiene and isoprene are preferred from the viewpoint of industrial availability.

Examples of aromatic vinyl compounds include styrene, p-methylstyrene, α-methylstyrene, vinylxylene, vinylnaphthalene, diphenylethylene 1-vinylnaphthalene, 3-vinyltoluene, ethylvinylbenzene, divinylbenzene, and 4-cyclohexane. Examples include xylstyrene and 2,4,6-trimethylstyrene. The aromatic vinyl compounds may be used alone or in combination of two or more. As the aromatic vinyl compound, styrene is preferred from the viewpoint of industrial availability.

Examples of conjugated diene polymers include natural rubber (NR), polybutadiene (BR), synthetic polyisoprene (IR), styrene-butadiene copolymer (SBR), isoprene-butadiene copolymer, ethylene-butadiene copolymer, and propylene. Examples include butadiene copolymers.

・Modified conjugated diene polymer (A1)
The modified conjugated diene polymer (A1) has a weight average molecular weight of 20×10 ⁴ to 300×10 ⁴ , and has a molecular weight of 200×10 ⁴ to 500 with respect to the total weight of the modified conjugated diene polymer (A1). It contains 0.25 to 30% by mass of the modified conjugated diene polymer having a molecular weight of 10 × 10 ⁴ and has a shrinkage factor (g') of less than 0.64.

The weight average molecular weight (Mw) of component (A1) is 20×10 ⁴ to 300×10 ⁴ . The above Mw is preferably 50×10 ⁴ or more, 64×10 ⁴ or more, or 80×10 ⁴ or more. Moreover, the above Mw is preferably 250×10 ⁴ or less, 180×10 ⁴ or less, or 150×10 ⁴ or less. When Mw is 20×10 ⁴ or more, it is possible to achieve both low rolling resistance and wet performance of the tire. Moreover, if Mw is 300×10 ⁴ or less, the processability of the rubber composition will improve.

Regarding the conjugated diene polymer and component (A1), the number average molecular weight, weight average molecular weight, molecular weight distribution, and content of specific high molecular weight components described below are measured as follows. Using a conjugated diene polymer or a modified conjugated diene polymer as a sample, a GPC (gel permeation chromatography) measuring device (trade name "HLC-" manufactured by Tosoh Corporation) consisting of three columns connected with polystyrene gel as a packing material is used. 8320GPC") and an RI detector (trade name "HLC-8020" manufactured by Tosoh Corporation), the weight average molecular weight was determined based on the calibration curve obtained using standard polystyrene. (Mw), number average molecular weight (Mn), molecular weight distribution (Mw/Mn), peak top molecular weight (Mp ₁ ) of modified conjugated diene polymer, peak top molecular weight (Mp ₂ ) of conjugated diene polymer, and its The ratio (Mp ₁ /Mp ₂ ) and the proportion of the modified conjugated diene polymer having a molecular weight of 200×10 ⁴ to 500×10 ⁴ are determined. THF (tetrahydrofuran) containing 5 mmol/L of triethylamine is used as the eluent. As the columns, three columns "TSKgel SuperMultiporeHZ-H" manufactured by Tosoh Corporation are connected, and a guard column "TSKguardcolumn SuperMP (HZ)-H" manufactured by Tosoh Corporation is connected in the preceding stage. 10 mg of a sample for measurement is dissolved in 10 mL of THF to obtain a measurement solution, and 10 μL of the measurement solution is injected into a GPC measuring device, and measurement is performed under the conditions of an oven temperature of 40° C. and a THF flow rate of 0.35 mL/min.

The peak top molecular weights (Mp ₁ and Mp ₂ ) are determined as follows. In the GPC curve obtained by measurement, the peak detected as the highest molecular weight component is selected. For the selected peak, the molecular weight corresponding to the maximum value of the peak is calculated and set as the peak top molecular weight.

The modified conjugated diene polymer (A1) has a molecular weight of 200×10 ⁴ to 500×10 ⁴ based on the total amount (100% by mass) of the modified conjugated diene polymer (A1). Contains 0.25 to 30% by mass of a polymer (also referred to herein as a "specific high molecular weight component"). If the content of the specific high molecular weight component is within this range, it is possible to achieve both low rolling resistance and wet performance of the tire.

Furthermore, the proportion of the modified conjugated diene polymer with a molecular weight of 200 x 10 ⁴ to 500 x 10 ⁴ is calculated from the integral molecular weight distribution curve, from the proportion of molecular weight of 500 x 10 ⁴ or less to the proportion of molecular weight of less than 200 x 10 ⁴ . Calculate by subtracting.

In one example, component (A1) includes a specific high molecular weight component of 1.0% by mass or more, 1.4% by mass or more, 1.75% by mass or more, 2.0% by mass or more, 2.15% by mass or more , or 2.5% by mass or more. In one example, component (A1) contains 28% by weight or less, 25% by weight or less, 20% by weight or less, or 18% by weight or less of the specific high molecular weight component.

In this specification, "molecular weight" is a standard polystyrene equivalent molecular weight obtained by GPC. In order to obtain component (A1) in which the content of the specific high molecular weight component is within such a range, it is preferable to control the reaction conditions in the polymerization step and reaction step described below. For example, in the polymerization step, the amount of the organic monolithium compound used as a polymerization initiator, which will be described later, may be adjusted. In addition, in the polymerization process, in both continuous and batch polymerization methods, it is preferable to use a method having a residence time distribution, that is, to widen the time distribution of the growth reaction.

In one example, component (A1) has a molecular weight distribution (Mw/Mn) of 1.6 to 3.0.

The shrinkage factor (g') of the modified conjugated diene polymer (A1) is less than 0.64. In general, branched polymers tend to have smaller molecular sizes when compared to linear polymers with the same absolute molecular weight, and the shrinkage factor (g') is assumed to be the same. It is an index of the ratio of the size occupied by molecules to the linear polymer, which is the absolute molecular weight of . That is, as the degree of branching of the polymer increases, the shrinkage factor (g') tends to decrease. In this embodiment, intrinsic viscosity is used as an index of molecular size, and a linear polymer is used as one that follows the relational expression of intrinsic viscosity [η]=-3.883M ^0.771 . Calculate the shrinkage factor (g') for each absolute molecular weight of the modified conjugated diene polymer, and calculate the average value of the shrinkage factor (g') when the absolute molecular weight is 100 x 10 ⁴ to 200 x 10 ⁴ . Define the contraction factor (g') of the modified conjugated diene polymer. Here, "branch" is formed by directly or indirectly bonding one polymer to another polymer. Moreover, "branching degree" is the number of polymers that are directly or indirectly bonded to each other for one branch. For example, when five conjugated diene polymer chains described below are indirectly bonded to each other via coupling residues described below, the degree of branching is 5. Note that the coupling residue is a structural unit of a modified conjugated diene polymer that is bonded to a conjugated diene polymer chain. This is a structural unit derived from a coupling agent. In addition, the conjugated diene polymer chain is a structural unit of a modified conjugated diene polymer. It is a structural unit.

The contraction factor (g') is, for example, 0.63 or less, 0.60 or less, 0.59 or less, or 0.57 or less. Further, the lower limit of the contraction factor (g') is not particularly limited, and may be lower than the detection limit value, for example, 0.30 or more, 0.33 or more, 0.35 or more, 0.45 or more, 0. 57 or more, or 0.59 or more. By using component (A1) having a shrinkage factor (g') within this range, the processability of the rubber composition is improved.

Since the shrinkage factor (g') tends to depend on the degree of branching, for example, the shrinkage factor (g') can be controlled using the degree of branching as an index. Specifically, in the case of a modified conjugated diene polymer with a degree of branching of 6, its shrinkage factor (g') tends to be 0.59 to 0.63, and the degree of branching is 8. When a modified conjugated diene polymer is used, its shrinkage factor (g') tends to be 0.45 to 0.59.

The method for measuring the contraction factor (g') is as follows. Using a modified conjugated diene polymer as a sample, a light scattering detector was measured using a GPC measuring device (product name: "GPCmax VE-2001" manufactured by Malvern) that had three columns connected with polystyrene gel as a packing material. , RI detector, and viscosity detector (trade name "TDA305" manufactured by Malvern). Based on standard polystyrene, the light scattering detector and RI detector are connected in this order. The absolute molecular weight is determined from the results of , and the intrinsic viscosity is determined from the results of the RI detector and viscosity detector. The linear polymer is used as having an intrinsic viscosity [η]=−3.883M ^0.771 , and the shrinkage factor (g′) as a ratio of the intrinsic viscosity corresponding to each molecular weight is calculated. THF containing 5 mmol/L of triethylamine is used as the eluent. The columns used are those manufactured by Tosoh Corporation under the trade names "TSKgel G4000HXL,""TSKgelG5000HXL," and "TSKgel G6000HXL." 20 mg of a sample for measurement is dissolved in 10 mL of THF to obtain a measurement solution, and 100 μL of the measurement solution is injected into a GPC measuring device and measured under the conditions of an oven temperature of 40° C. and a THF flow rate of 1 mL/min.

The amount of extender oil added to component (A1) may be adjusted as appropriate, for example, 1 to 40 parts by mass, 1 to 35 parts by mass, or 1 to 10 parts by mass per 100 parts by mass of component (A1). It is. In another example, the amount of extender oil added to component (A1) is greater than 0 parts by mass and 10 parts by mass or less based on 100 parts by mass of component (A1).

Examples of the extender oil include aroma oil, naphthenic oil, paraffin oil, and aroma substitute oil. Among these, from the viewpoint of environmental safety, prevention of oil bleed, and wet braking performance, aromatic alternative oils containing 3% by mass or less of polycyclic aromatic (PCA) components according to the IP346 method are preferred. As aroma substitute oils, TDAE (Treated Distillate Aromatic Extracts) and MES (Mild Extraction Solvate) shown in Kautschuk Gummi Kunststoffe 52 (12) 799 (1999) are used. Other examples include RAE (Residual Aromatic Extracts).

Component (A1) can be an oil-extended polymer to which an extender oil has been added, and may be non-oil-extended or oil-extended.

Component (A1) preferably has branching, and the degree of branching is preferably 5 or more. In addition, component (A1) has one or more coupling residues and a conjugated diene polymer chain bonded to the coupling residues, and further, the branch has one of the coupling residues. It is more preferable that the group includes a branch to which five or more conjugated diene polymer chains are bonded. The structure of the modified conjugated diene polymer is such that the degree of branching is 5 or more, and the branching includes a branch in which 5 or more conjugated diene polymer chains are bonded to one coupling residue. By specifying , the contraction factor (g') can be more reliably set to less than 0.64. Note that the number of conjugated diene polymer chains bonded to one coupling residue can be confirmed from the value of the contraction factor (g').

Moreover, it is more preferable that component (A1) has branching and the degree of branching is 6 or more. In addition, component (A1) has one or more coupling residues and a conjugated diene polymer chain bonded to the coupling residues, and further, the branch has one of the coupling residues. More preferably, the group includes a branch in which six or more conjugated diene polymer chains are bonded to the group. The structure of the modified conjugated diene polymer is such that the degree of branching is 6 or more, and the branching includes a branch in which 6 or more conjugated diene polymer chains are bonded to one coupling residue. By specifying , the contraction factor (g') can be set to 0.63 or less.

Furthermore, component (A1) has branching, and the degree of branching is more preferably 7 or more, and even more preferably 8 or more. The upper limit of the degree of branching is not particularly limited, but is preferably 18 or less. In addition, component (A1) has one or more coupling residues and a conjugated diene polymer chain bonded to the coupling residues, and further, the branch has one of the coupling residues. It is even more preferable to include a branch in which seven or more conjugated diene polymer chains are bonded to the group, and eight or more conjugated diene polymer chains are bonded to one coupling residue. It is particularly preferred to include branches that are connected. The structure of the modified conjugated diene polymer is such that the degree of branching is 8 or more, and the branching includes a branch in which 8 or more conjugated diene polymer chains are bonded to one coupling residue. By specifying , the contraction factor (g') can be made 0.59 or less.

The modified conjugated diene polymer (A1) has the following general formula (I):
[In general formula (I), D represents a conjugated diene polymer chain, R ¹ , R ² and R ³ each independently represent a single bond or an alkylene group having 1 to 20 carbon atoms, R ⁴ and R ⁷ each independently represent an alkyl group having 1 to 20 carbon atoms; R ⁵ , R ⁸ , and R ⁹ each independently represent a hydrogen atom or an alkyl group having 1 to 20 carbon atoms; ⁶ and R ¹⁰ each independently represent an alkylene group having 1 to 20 carbon atoms, R ¹¹ represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, and m and x each independently represent 1 to 20 carbon atoms. represents an integer of 3, x≦m, p represents 1 or 2, y represents an integer from 1 to 3, y≦(p+1), z represents 1 or 2, respectively. When a plurality of D, R ¹ to R ¹¹ , m, p, x, y, and z are independent, i represents an integer from 0 to 6, and j represents an integer from 0 to 6. , k is an integer from 0 to 6, (i+j+k) is an integer from 3 to 10, and ((x×i)+(y×j)+(z×k)) is an integer from 5 to 10. is an integer of 30, A has a hydrocarbon group having 1 to 20 carbon atoms, or at least one atom selected from the group consisting of oxygen atom, nitrogen atom, silicon atom, sulfur atom and phosphorus atom, and represents an organic group having no active hydrogen.
This makes it possible to achieve a higher balance between wet performance, wear resistance, low rolling resistance, and fracture resistance.

In one example, the weight average molecular weight of the conjugated diene polymer chain represented by D in general formula (I) is 10×10 ⁴ to 100×10 ⁴ . The conjugated diene polymer chain is a structural unit of a modified conjugated diene polymer, and is, for example, a structural unit derived from a conjugated diene polymer produced by reacting a conjugated diene polymer with a coupling agent. be.

In general formula (I), the hydrocarbon group represented by A includes saturated, unsaturated, aliphatic, and aromatic hydrocarbon groups. Examples of the above-mentioned organic groups without active hydrogen include active hydrogen groups such as hydroxyl group (-OH), secondary amino group (>NH), primary amino group (-NH ₂ ), and sulfhydryl group (-SH). Examples include a functional group having , and an organic group not having .

In general formula (I), A represents the following general formulas (II) to (V):
[In general formula (II), B ¹ represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, a represents an integer of 1 to 10, and when a plurality of B ^1s exist, each independently ing;
In the general formula (III), B ² represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, B ³ represents an alkyl group having 1 to 20 carbon atoms, and a represents an integer of 1 to 10. and B ² and B ³ in the case where a plurality of each exists are each independent;
In the general formula (IV), B ⁴ represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, a represents an integer of 1 to 10, and when a plurality of B 4 exist, each B ⁴ independently There is;
In the general formula (V), B ⁵ represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, a represents an integer of 1 to 10, and when a plurality of B 5 exist, each B ⁵ is independently It is preferable to express it as one of the following.
This makes it possible to achieve a higher balance between wet performance, wear resistance, low rolling resistance, and fracture resistance.

In one example, in the general formula (I), A is represented by the general formula (II) or (III), and k represents 0. In another example, in the general formula (I), A is represented by the general formula (II) or (III), k represents 0, and in the general formula (II) or (III), a represents an integer from 2 to 10. In yet another example, in the general formula (I), A is represented by the general formula (II), k represents 0, and in the general formula (II), a is an integer of 2 to 10. shows.

Regarding B ¹ , B ² , B ⁴ , and B ⁵ in general formulas (II) to (V), examples of the hydrocarbon group having 1 to 20 carbon atoms include alkylene groups having 1 to 20 carbon atoms.

Component (A1) preferably contains a nitrogen atom and a silicon atom. In this case, the processability of the rubber composition becomes good, and when applied to a tire, it is possible to further improve the low rolling resistance while improving the wet braking performance and abrasion resistance of the tire. Regarding the component (A1) having a nitrogen atom, it is determined that the component (A1) has a nitrogen atom if the calculated modification rate is 10% or more using the modification rate measurement method described below.

Whether component (A1) has a silicon atom is determined by the following method. Using 0.5 g of a modified conjugated diene polymer as a sample, it was measured using an ultraviolet-visible spectrophotometer (trade name "UV-1800" manufactured by Shimadzu Corporation) in accordance with JIS K 0101 44.3.1. , determined by molybdenum blue spectrophotometry. As a result, if silicon atoms are detected (lower detection limit: 10 mass ppm), it is determined that silicon atoms are present.

In one example, at least one terminal of the conjugated diene polymer chain is bonded to a silicon atom of each coupling residue. In this case, the ends of a plurality of conjugated diene polymer chains may be bonded to one silicon atom. In addition, the terminal of the conjugated diene polymer chain and the alkoxy group or hydroxyl group having 1 to 20 carbon atoms are bonded to one silicon atom, and as a result, the silicon atom is bonded to the alkoxysilyl group having 1 to 20 carbon atoms. or a silanol group.

The amount of bound conjugated diene in the conjugated diene polymer or component (A1) is, for example, 40 to 100% by mass, or 55 to 80% by mass. When the amount of bonded conjugated diene is within the above range, wet performance, abrasion resistance, low rolling resistance, and fracture resistance properties can be more highly balanced when the rubber composition is applied to a tire. It becomes possible.

Further, the amount of bonded aromatic vinyl in the conjugated diene polymer or component (A1) is, for example, 0% by mass or more, 20% by mass or more, or 35% by mass or more. Further, the amount of bonded aromatic vinyl in the conjugated diene polymer or component (A1) is, for example, 60% by mass or less, or 45% by mass or less. When the amount of bonded aromatic vinyl is within the above range, wet performance, abrasion resistance, low rolling resistance, and fracture resistance properties can be more highly balanced when the rubber composition is applied to a tire. becomes possible.

The amount of bonded aromatic vinyl can be measured by ultraviolet absorption of the phenyl group, and from this, the amount of bonded conjugated diene can also be determined. Specifically, it is measured according to the following. Using a modified conjugated diene polymer as a sample, 100 mg of the sample is diluted to 100 mL with chloroform and dissolved to obtain a measurement sample. Measure the amount of bound styrene (mass%) with respect to 100 mass% of the sample based on the absorption amount of ultraviolet absorption wavelength (around 254 nm) by the phenyl group of styrene (spectrophotometer "UV-2450" manufactured by Shimadzu Corporation) .

In the conjugated diene polymer or component (A1), the amount of vinyl bonds in the conjugated diene bond units is, for example, 10 to 75 mol%, or 20 to 65 mol%.

When component (A1) is a copolymer of butadiene and styrene, the method of Hampton [R. R. Hampton, Analytical Chemistry, 21, 923 (1949)], the amount of vinyl bonds (1,2-bond amount) in the butadiene bond unit can be determined. Specifically, it is as follows. Using a modified conjugated diene polymer as a sample, 50 mg of the sample is dissolved in 10 mL of carbon disulfide to prepare a measurement sample. Using a solution cell, the infrared spectrum was measured in the range of 600 to 1000 cm ^-1 , and the microstructure of the butadiene moiety, that is, the 1,2-vinyl bond, was determined by the absorbance at a predetermined wave number according to the calculation formula of Hampton's method. The amount (mol%) is determined (Fourier transform infrared spectrophotometer "FT-IR230" manufactured by JASCO Corporation).

Component (A1) preferably has a Tg higher than -50°C, more preferably -45 to -15°C. When the Tg of component (A1) is in the range of -45 to -15°C, when the rubber composition is applied to a tire, wet performance, abrasion resistance, low rolling resistance, and fracture resistance are improved. It is possible to achieve a higher degree of compatibility.

Regarding Tg, according to ISO 22768:2006, a DSC curve is recorded while increasing the temperature in a predetermined temperature range, and the peak top (inflection point) of the DSC differential curve is defined as Tg. Specifically, it is as follows. Using a modified conjugated diene polymer as a sample, temperature was measured from -100°C to 20°C/min under helium flow of 50 mL/min using a differential scanning calorimeter "DSC3200S" manufactured by Mac Science in accordance with ISO 22768:2006. A DSC curve is recorded while the temperature is raised at , and the peak top (inflection point) of the DSC differential curve is set as Tg.

In the rubber composition according to the present invention, it is preferable that the difference in glass transition temperature (Tg) between the modified conjugated diene polymer (A1) and the modified conjugated diene polymer (A2) is 20° C. or more.
Thereby, wear resistance can be further improved.

In one example, the Tg difference between component (A1) and component (A2) is 20 to 40°C.

Component (A1) has a Mooney viscosity of, for example, 20 to 100, or 30 to 80, measured at 100°C.

The method for measuring Mooney viscosity is as follows. Using a conjugated diene polymer or a modified conjugated diene polymer as a sample, measure the Mooney viscosity using a Mooney viscometer (product name "VR1132" manufactured by Ueshima Seisakusho Co., Ltd.) using an L-shaped rotor in accordance with JIS K6300. do. The measurement temperature is 110° C. when a conjugated diene polymer is used as a sample, and 100° C. when a modified conjugated diene polymer is used as a sample. First, after preheating the sample at the test temperature for 1 minute, the rotor is rotated at 2 rpm, and the torque after 4 minutes is measured and defined as the Mooney viscosity (ML ₍₁₊₄₎ ).

In one embodiment, component (A1) is a modified styrene butadiene rubber.

In the rubber composition according to the present invention, it is preferable that the modified conjugated diene polymer (A1) and the modified conjugated diene polymer (A2) are modified styrene-butadiene rubbers.
This makes it possible to achieve a more advanced balance between low rolling resistance and wet performance.

・Method for synthesizing modified conjugated diene polymer (A1) The method for synthesizing component (A1) is not particularly limited. For example, an organic monolithium compound is used as a polymerization initiator, and at least a conjugated diene compound is polymerized. , a polymerization step for obtaining a conjugated diene polymer, and a reaction step for reacting a penta- or higher-functional reactive compound (hereinafter also referred to as a "coupling agent") with the active end of the conjugated diene polymer. Examples include a synthesis method having the following.

Examples of the polymerization step include polymerization by a growth reaction using a living anion polymerization reaction. Thereby, a conjugated diene polymer having an active end can be obtained, and a component (A1) with a high modification rate can be obtained.

The amount of the organic monolithium compound used as a polymerization initiator can be adjusted depending on the molecular weight of the target conjugated diene polymer or modified conjugated diene polymer. Decreasing the amount of polymerization initiator increases the molecular weight, while increasing the amount of polymerization initiator decreases the molecular weight.

The organic monolithium compound is preferably an alkyllithium compound from the viewpoint of industrial availability and ease of controlling the polymerization reaction. In this case, a conjugated diene polymer having an alkyl group at the polymerization initiation terminal is obtained.

Examples of the alkyllithium compound include n-butyllithium, sec-butyllithium, tert-butyllithium, n-hexyllithium, benzyllithium, phenyllithium, and stilbenelithium. These organic monolithium compounds may be used alone or in combination of two or more.

In the polymerization step, a batch type or continuous type polymerization reaction mode can be appropriately selected and used.

In the polymerization step, an inert solvent may be used.

Examples of inert solvents include aliphatic hydrocarbons such as butane, pentane, hexane, and heptane; alicyclic hydrocarbons such as cyclopentane, cyclohexane, methylcyclopentane, and methylcyclohexane; and aromatic solvents such as benzene, toluene, and xylene. Examples include hydrocarbons. The inert solvents may be used alone or in combination of two or more.

Before using the inert solvent in the polymerization reaction, it may be treated with an organometallic compound in order to remove arenes and acetylenes which are impurities in the inert solvent.

A polar compound may be used in the polymerization step. By using a polar compound, an aromatic vinyl compound can be randomly copolymerized with a conjugated diene compound. The polar compound can also be used as a vinylating agent to control the microstructure of the conjugated diene moiety.

Examples of polar compounds include ethers such as tetrahydrofuran, diethyl ether, dioxane, ethylene glycol dimethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol dibutyl ether, dimethoxybenzene, and 2,2-bis(2-oxolanyl)propane; Tertiary amine compounds such as methylethylenediamine, dipiperidinoethane, trimethylamine, triethylamine, pyridine, quinuclidine; alkali metal alkoxides such as potassium-tert-amylate, potassium-tert-butyrate, sodium-tert-butyrate, sodium amylate, etc. Compounds include phosphine compounds such as triphenylphosphine. The polar compounds may be used alone or in combination of two or more.

The polymerization temperature in the polymerization step may be adjusted as appropriate, and is, for example, 0 to 120°C or 50 to 100°C from the viewpoint of ensuring a sufficient amount of reaction of the coupling agent to the active terminal after completion of polymerization.

Examples of the coupling agent include a pentafunctional or higher functional reactive compound having a nitrogen atom and a silicon atom. Preferably, the reactive compound has at least three silicon-containing functional groups. The coupling agent is preferably one in which at least one silicon atom constitutes an alkoxysilyl group or silanol group having 1 to 20 carbon atoms, and more preferably a compound represented by the general formula (VI) described below. It is. The coupling agents may be used alone or in combination of two or more.

For example, the alkoxysilyl group of the coupling agent reacts with the active end of the conjugated diene polymer, dissociating the alkoxylithium, and bonding the end of the conjugated diene polymer chain with the silicon of the coupling residue. tend to form. The value obtained by subtracting the number of SiORs reduced by the reaction from the total number of SiORs that one molecule of the coupling agent has is the number of alkoxysilyl groups that the coupling residue has. Further, the azasilacycle group possessed by the coupling agent forms a >N-Li bond and a bond between the terminal of the conjugated diene polymer and the silicon of the coupling residue. Note that >N—Li bonds tend to easily become >NH and LiOH due to water and the like during finishing. Furthermore, unreacted and remaining alkoxysilyl groups in the coupling agent can easily become silanol (Si--OH group) due to water during finishing.

The modified conjugated diene polymer (A1) is a conjugated diene polymer formed by the following general formula (VI):
[In general formula (VI), R ¹² , R ¹³ and R ¹⁴ each independently represent a single bond or an alkylene group having 1 to 20 carbon atoms, R ¹⁵ , R ¹⁶ , R ¹⁷ , R ¹⁸ and R ²⁰ each independently represents an alkyl group having 1 to 20 carbon atoms, R ¹⁹ and R ²² each independently represents an alkylene group having 1 to 20 carbon atoms, and R ²¹ represents an alkylene group having 1 to 20 carbon atoms. represents an alkyl group or a trialkylsilyl group, m represents an integer of 1 to 3, p represents 1 or 2, and R ¹² to R ²² , m and p each independently represent a plurality of them. i, j and k each independently represent an integer of 0 to 6, provided that (i+j+k) is an integer of 3 to 10, and A is a hydrocarbon group having 1 to 20 carbon atoms, or , an organic group having at least one type of atom selected from the group consisting of oxygen atom, nitrogen atom, silicon atom, sulfur atom and phosphorus atom and having no active hydrogen] Preferably, it is made to react.
This makes it possible to achieve a higher balance between wet performance, wear resistance, low rolling resistance, and fracture resistance.

In the general formula (VI), the hydrocarbon group represented by A includes saturated, unsaturated, aliphatic, and aromatic hydrocarbon groups. Examples of organic groups that do not have active hydrogen include hydroxyl group (-OH), secondary amino group (>NH), primary amino group (-NH ₂ ), and sulfhydryl group (-SH). Examples include functional groups with and organic groups without.

In one example, in the general formula (VI), A is represented by the general formula (II) or (III), and k represents 0. In another example, in the general formula (VI), A is represented by the general formula (II) or (III), k represents 0, and in the general formula (II) or (III), a represents an integer from 2 to 10. In yet another example, in the general formula (VI), A is represented by the general formula (II), k represents 0, and in the general formula (II), a is an integer of 2 to 10. shows.

Examples of such coupling agents include tetrakis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, tetrakis(3-trimethoxysilylpropyl) )-1,3-propanediamine, tetrakis(3-trimethoxysilylpropyl)-1,3-bisaminomethylcyclohexane, bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1- aza-2-silacyclopentane)propyl]amine, tris(3-trimethoxysilylpropyl)amine, tris(3-triethoxysilylpropyl)amine, tris(3-trimethoxysilylpropyl)-[3-(2, 2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, tris(3-trimethoxysilylpropyl)-methyl-1,3-propanediamine, bis[3-(2, Examples include 2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trismethoxysilylpropyl)-methyl-1,3-propanediamine.

The amount of the compound represented by the general formula (VI) as a coupling agent is adjusted so that the number of moles of the conjugated diene polymer to the number of moles of the coupling agent is reacted in a desired stoichiometric ratio. This tends to achieve the desired degree of branching. Specifically, the number of moles of the polymerization initiator is, for example, 5.0 times or more, or 6.0 times or more, relative to the number of moles of the coupling agent. In this case, in the general formula (VI), the number of functional groups ((m-1)×i+p×j+k) of the coupling agent is an integer of 5 to 10, or an integer of 6 to 10.

The reaction temperature in the reaction step may be adjusted as appropriate, and is, for example, 0 to 120°C or 50 to 100°C. Further, the temperature change after the polymerization step until the coupling agent is added is, for example, 10°C or less, or 5°C or less.

The reaction time in the reaction step may be adjusted as appropriate, and is, for example, 10 seconds or more, or 30 seconds or more. The time from the end of the polymerization step to the start of the reaction step is preferably shorter, for example, within 5 minutes, from the viewpoint of the coupling rate.

Mixing in the reaction step may be performed by mechanical stirring, stirring using a static mixer, or the like.

In order to obtain the component (A1) having the specific high molecular weight component, the molecular weight distribution (Mw/Mn) of the conjugated diene polymer is set to 1.5 to 2.5 or 1.8 to 2.2. It's good to do that. Moreover, it is preferable that the obtained component (A1) has a single peak detected in the molecular weight curve by GPC.

In one example, when the peak molecular weight of component (A1) by GPC is Mp ₁ and the peak molecular weight of the conjugated diene polymer is Mp ₂ , the following formula holds true.
(Mp ₁ /Mp ₂ )<1.8×10-12×(Mp ₂ -120×10 ⁴ ) ² +2

In one example, Mp ₂ is between 20×10 ⁴ and 80×10 ⁴ and Mp ₁ is between 30×10 ⁴ and 150×10 ⁴ .

The modification rate of component (A1) is, for example, 30% by mass or more, 50% by mass or more, or 70% by mass or more. By having a modification rate of 30% by mass or more, when the rubber composition is applied to a tire, it is possible to further improve the low rolling resistance while improving the wear resistance of the tire.

The method for measuring the denaturation rate is as follows. Using a modified conjugated diene polymer as a sample, it is measured by applying the property of adsorption of modified basic polymer components to a GPC column using silica gel as a filler. The amount of adsorption to the silica column is measured from the difference between the chromatogram measured using a polystyrene column and the chromatogram measured using a silica column for a sample solution containing a sample and a low molecular weight internal standard polystyrene, and the denaturation rate is determined. demand. Specifically, it is as shown below.
Preparation of sample solution: 10 mg of sample and 5 mg of standard polystyrene are dissolved in 20 mL of THF to prepare a sample solution.
GPC measurement conditions using a polystyrene column: Using Tosoh Corporation's product name "HLC-8320GPC," using THF containing 5 mmol/L triethylamine as the eluent, 10 μL of the sample solution was injected into the device, and the column oven was heated. A chromatogram is obtained using an RI detector at a temperature of 40° C. and a THF flow rate of 0.35 mL/min. As the columns, three columns "TSKgel SuperMultiporeHZ-H" manufactured by Tosoh Corporation are connected, and a guard column "TSKguardcolumn SuperMP (HZ)-H" manufactured by Tosoh Corporation is connected in the preceding stage.
GPC measurement conditions using a silica column: Using Tosoh's product name "HLC-8320GPC", using THF as the eluent, injecting 50 μL of the sample solution into the device, column oven temperature 40°C, THF flow rate. A chromatogram is obtained using an RI detector at 0.5 ml/min. Columns with the product name "Zorbax PSM-1000S", "PSM-300S", and "PSM-60S" are connected and used, and the product name "DIOL 4.6 x 12.5 mm 5 micron" is used as a guard column in the preceding stage. Connect and use.
Calculation method for denaturation rate: Taking the total peak area of the chromatogram using a polystyrene column as 100, the peak area of the sample is P1, the peak area of standard polystyrene is P2, and the peak area of the chromatogram using a silica column is The modification rate (%) is determined from the following formula, setting the total as 100, setting the peak area of the sample as P3, and setting the peak area of standard polystyrene as P4.
Denaturation rate (%) = [1-(P2×P3)/(P1×P4)]×100
(However, P1+P2=P3+P4=100)

After the reaction step, a deactivator, a neutralizing agent, etc. may be added to the copolymer solution, if necessary. Examples of the deactivator include water; alcohols such as methanol, ethanol, and isopropanol; and the like. Examples of neutralizing agents include carboxylic acids such as stearic acid, oleic acid, and versatic acid (a highly branched carboxylic acid mixture with 9 to 11 carbon atoms, mainly 10 carbon atoms); aqueous solutions of inorganic acids, and carbonic acid. Examples include gas.

Component (A1) is, for example, 2,6-di-tert-butyl-4-hydroxytoluene (BHT), n- Antioxidants such as octadecyl-3-(4'-hydroxy-3',5'-di-tert-butylphenol)propinate and 2-methyl-4,6-bis[(octylthio)methyl]phenol may be added. preferable.

In order to further improve the processability of component (A1), extender oil may be added to the modified conjugated diene copolymer, if necessary. Examples of the method for adding the extender oil to the modified conjugated diene polymer include a method in which the extender oil is added to a polymer solution, mixed, and the resulting oil-extended copolymer solution is desolvated.

A known method can be used to obtain component (A1) from the polymer solution. Examples of this method include, for example, separating the solvent by steam stripping, filtering the polymer, dehydrating and drying it to obtain a polymer, concentrating it in a flushing tank, and then using a vent extruder. Examples include a method of devolatilizing with a drum dryer, and a method of directly devolatilizing with a drum dryer.

The amount of component (A1) in the rubber component may be adjusted as appropriate, for example, 10 parts by mass or more, 20 parts by mass or more, 30 parts by mass or more, 40 parts by mass or more, based on 100 parts by mass of the rubber component. 50 parts by mass or more, and for example, the amount of component (A1) is 90 parts by mass or less, 80 parts by mass or less, 70 parts by mass or less, 60 parts by mass or less, 50 parts by mass, based on 100 parts by mass of the rubber component. part or less, 40 parts by mass or less, or 30 parts by mass or less.

In the rubber composition according to the present invention, the total amount of the modified conjugated diene polymer (A1) and the modified conjugated diene polymer (A2) described below is 50 parts by mass or more based on 100 parts by mass of the rubber component. It is preferable that
Thereby, the filler can be distributed more into the polymer phase (1) and the filler can be more highly dispersed in the polymer phase (1).

・Modified conjugated diene polymer (A2)
The modified conjugated diene polymer (A2) is a modified conjugated diene polymer different from the modified conjugated diene polymer (A1). However, since component (A1) and component (A2) are both modified conjugated diene polymers, they are included in the polymer phase (1).

The conjugated diene polymer that is the base polymer of component (A2) is, for example, the above-mentioned polybutadiene (BR), synthetic polyisoprene (IR), styrene-butadiene copolymer (SBR), isoprene-butadiene copolymer, or ethylene-butadiene copolymer. Examples include polymers, propylene butadiene copolymers, and the like.

In one embodiment, component (A2) is a modified styrene butadiene rubber.

The modified SBR as component (A2) may be different from component (A1), and any known modified SBR may be used. Examples include modified SBRs described in JP2017-190457A, WO2016/194316, WO2017/077712, and WO2017/077714.

The modifier for obtaining the modified SBR as component (A2) can be appropriately selected from known modifiers. In order to have high interaction with fillers (for example, silica), the modifier is preferably one or more selected from the group consisting of alkoxysilane compounds, hydrocarbyloxysilane compounds, and combinations thereof.

Examples of the alkoxysilane compound include N-(1,3-dimethylbutylidene)-3-triethoxysilyl-1-propanamine, tetramethoxysilane, tetraethoxysilane, tetra-n-propoxysilane, tetraisopropoxysilane, Tetra-n-butoxysilane, tetraisobutoxysilane, tetra-sec-butoxysilane, tetra-tert-butoxysilane, methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltriisopropoxysilane, ethyltrimethoxy Silane, ethyltriethoxysilane, ethyltripropoxysilane, ethyltriisopropoxysilane, propyltrimethoxysilane, propyltriethoxysilane, propyltripropoxysilane, propyltriisopropoxysilane, butyltrimethoxysilane, butyltriethoxysilane, phenyl Examples include trimethoxysilane, phenyltriethoxysilane, dimethridimethoxysilane, methylphenyldimethoxysilane, dimethyldiethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, and divinyldiethoxysilane. Among these, N-(1,3-dimethylbutylidene)-3-(triethoxysilyl)-1-propanamine, tetraethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane and the like can be mentioned. One type of alkoxysilane compound may be used alone, or two or more types may be used in combination.

Hydrocarbyloxysilane compounds include, for example, [N,N-bis(trimethylsilyl)-(3-amino-1-propyl)](methyl)(diethoxy)silane, N1,N1,N7-tetramethyl-4-((trimethylsilyl)), methoxysilyl)methyl)-1,7heptane, 2-((hexyl-dimethoxysilyl)methyl)-N1,N1,N3,N3-2-pentamethylpropane-1,3-diamine, N1-(3-( dimethylamino)propyl-N3,N3-dimethyl-N1-(3-(trimethoxysilyl)propyl)propane-1,3-diamine, 4-(3-(dimethylamino)propyl)-N1,N1,N7,N7 -Tetramethyl-4-((trimethoxysilyl)methyl)heptane-1,7-diamine; N,N-dimethyl-2-(3-(dimethoxymethylsilyl)propoxy)ethanamine, N,N-bis(trimethylsilyl) )-2-(3-(trimethoxysilyl)propoxy)ethanamine, N,N-dimethyl-2-(3-(trimethoxysilyl)propoxy)ethanamine, N,N-dimethyl-3-(3-(trimethoxysilyl)propoxy)-2-(3-(trimethoxysilyl)propoxy)ethanamine Examples include silyl)propoxy)propan-1-amine.

Suitable modifiers for obtaining modified SBR as component (A2) by anionic polymerization include, for example, 3,4-bis(trimethylsilyloxy)-1-vinylbenzene, 3,4-bis(trimethylsilyloxy)benzaldehyde, At least one compound selected from 3,4-bis(tert-butyldimethylsilyloxy)benzaldehyde, 2-cyanopyridine, 1,3-dimethyl-2-imidazolidinone, and 1-methyl-2-pyrrolidone is mentioned. .

The modifier is preferably an amide moiety of a lithium amide compound used as a polymerization initiator in anionic polymerization. Examples of such lithium amide compounds include lithium hexamethyleneimide, lithium pyrrolidide, lithium piperidide, lithium heptamethyleneimide, lithium dodecamethyleneimide, lithium dimethylamide, lithium diethylamide, lithium dibutylamide, and lithium dipropyl. Amide, lithium diheptylamide, lithium dihexylamide, lithium dioctylamide, lithium di-2-ethylhexylamide, lithium didecylamide, lithium-N-methylpiverazide, lithium ethylpropylamide, lithium ethylbutylamide, lithium ethylbenzylamide, lithium methyl Includes phenethylamide and combinations thereof. For example, the modifier that becomes the amide moiety of lithium hexamethyleneimide is hexamethyleneimine, the modifier that becomes the amide moiety of lithium pyrrolidide is pyrrolidine, and the modifier that becomes the amide moiety of lithium piperidide is piperidine. .

When the modified SBR as component (A2) is obtained by coordination polymerization, suitable modifiers include, for example, at least one compound selected from 2-cyanopyridine and 3,4-ditrimethylsilyloxybenzaldehyde.

When the modified SBR as component (A2) is obtained by emulsion polymerization, suitable modifiers include, for example, at least one compound selected from 3,4-ditrimethylsilyloxybenzaldehyde and 4-hexamethyleneiminoalkylstyrene. It will be done. These modifiers preferably used in emulsion polymerization are preferably copolymerized as monomers containing nitrogen atoms and/or silicon atoms during emulsion polymerization.

The modification rate of the modified SBR as component (A2) is, for example, 30% or more, 35% or more, or 70% or more. The higher the modification rate, when the filler contains silica, the more the filler is distributed in the polymer phase (1), and the wet performance can be further improved.

The Tg of component (A2) is, for example, -40°C or lower, -50°C or lower, or -60°C or lower. Further, the Tg of component (A2) is, for example, -70°C or higher, -60°C or higher, or -50°C or higher.

The amount of component (A2) in the rubber component may be adjusted as appropriate, for example, 10 parts by mass or more, 20 parts by mass or more, 30 parts by mass or more, 40 parts by mass or more, based on 100 parts by mass of the rubber component. It is 50 parts by mass or more. For example, the amount of component (A2) is 90 parts by mass or less, 80 parts by mass or less, 70 parts by mass or less, 60 parts by mass or less, 50 parts by mass or less, 40 parts by mass or less, based on 100 parts by mass of the rubber component. , or 30 parts by mass or less.

-Third polymer The third polymer is a polymer different from component (A1) and component (A2). The third polymer may be selected appropriately, and examples thereof include natural rubber (NR), polybutadiene (BR), synthetic polyisoprene (IR), styrene-butadiene copolymer (SBR), isoprene-butadiene copolymer, and ethylene-butadiene copolymer. Examples include propylene butadiene copolymer and propylene butadiene copolymer.

In one embodiment, the third polymer is one selected from the group consisting of natural rubber, synthetic isoprene rubber, and butadiene rubber (hi-cis BR) having a cis-1,4 content of 90% by mass or more.

In the rubber composition according to the present invention, the polymer phase (2) preferably contains natural rubber, synthetic isoprene rubber, or butadiene rubber (high-cis BR) having a cis-1,4 content of 90% by mass or more.
This increases the difference in Tg between the polymer phase (1) and the polymer phase with the lowest peak temperature, making it possible to reliably make these phases incompatible.

The amount of the third polymer in the rubber component may be adjusted as appropriate, for example, 10 parts by mass or more, 20 parts by mass or more, 30 parts by mass or more, 40 parts by mass or more, 50 parts by mass or more, based on 100 parts by mass of the rubber component. The amount is at least 60 parts by mass, or at least 70 parts by mass. Further, for example, the amount of the third polymer in the rubber component is 90 parts by mass or less, 80 parts by mass or less, 70 parts by mass or less, 60 parts by mass or less, 50 parts by mass or less, based on 100 parts by mass of the rubber component. It is 40 parts by mass or less, 30 parts by mass or less, or 20 parts by mass or less.

<Filler>
The rubber composition according to the present invention contains a filler. Examples of fillers include silica, carbon black, aluminum hydroxide, clay, alumina, talc, mica, kaolin, glass balloons, glass beads, calcium carbonate, magnesium carbonate, magnesium hydroxide, magnesium oxide, titanium oxide, potassium titanate. , barium sulfate, etc.

In one embodiment, the fillers are silica and carbon black. In another embodiment, the filler is silica.

Silica can be appropriately selected depending on the purpose, and includes, for example, wet silica (hydrated silicic acid), dry silica (anhydrous silicic acid), calcium silicate, aluminum silicate, and the like. Silica may be used alone or in combination of two or more.

The BET specific surface area of silica may be selected as appropriate, for example, from 40 to 350 ^{m 2} /g, from 80 to 300 m ² /g, or from 150 to 280 m ² /g.

The BET specific surface area refers to a specific surface area determined by the BET method, and in the present invention refers to a value measured in accordance with ASTM D4820-93.

The proportion of silica in the filler may be adjusted as appropriate, for example, 50% by mass or more, 60% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, or It is 95% by mass or more. For example, the proportion of silica in the filler is 100% by mass or less, less than 100% by mass, 95% by mass or less, 90% by mass or less, 80% by mass or less, 70% by mass or less, based on the total mass of the filler. It is 60% by mass or less, or 50% by mass or less.

Carbon blacks include, for example, high, medium or low structure carbon blacks such as SAF, ISAF, ISAF-HS, IISAF, N339, HAF, FEF, GPF, SRF grades. Carbon black may be used alone or in combination of two or more.

The BET specific surface area of carbon black may be selected as appropriate, for example, from 40 to 350 m ² /g or from 80 to 200 m ² /g.

The proportion of carbon black in the filler may be adjusted as appropriate, for example, 1% by mass or more, 2% by mass or more, 3% by mass or more, 4% by mass or more, 5% by mass or more, based on the total mass of the filler. It is 10% by mass or more, 20% by mass or more, or 30% by mass or more. For example, the proportion of carbon black in the filler is 100% by mass or less, less than 100% by mass, 50% by mass or less, 40% by mass or less, 30% by mass or less, 20% by mass or less, based on the total mass of the filler. , 10% by mass or less, or 5% by mass or less.

The blending amount of the filler may be adjusted as appropriate, and is, for example, 50 to 120 parts by mass based on 100 parts by mass of the rubber component.

In addition to the rubber component and filler, the rubber composition according to the present invention includes components commonly used in the rubber industry, such as a styrene-alkylene block copolymer, a thermoplastic resin, a softener, a vulcanization accelerator, A silane coupling agent, a vulcanizing agent, a glycerin fatty acid ester, an anti-aging agent, a vulcanization accelerator, an organic acid compound, etc. can be appropriately selected and contained within the scope of the invention.

(Method for preparing rubber composition)
The method for preparing the rubber composition according to the present invention is not particularly limited, and components such as a rubber component and filler may be kneaded using a known kneading method.

The rubber composition according to the present invention is preferably used for tires, more preferably for tire tread rubber.

(tread rubber)
The tread rubber according to the present invention is a tread rubber using any of the rubber compositions described above.
Thereby, the wet performance, abrasion resistance, low rolling resistance, and fracture resistance of the tread rubber can be highly balanced.

(tire)
A tire according to the present invention is a tire using any of the rubber compositions described above.
This makes it possible to highly balance the tire's wet performance, wear resistance, low rolling resistance, and fracture resistance.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but these Examples are intended to illustrate the present invention and are not intended to limit the present invention in any way. The blending amount means parts by mass unless otherwise specified.

The materials used in the examples are as follows.

Rubber component Natural rubber (NR): Product name “SIR20” made in Indonesia
Hysis BR: Product name “JSRBR01 (registered trademark)” manufactured by JSR Corporation
Modified SBR (3): Asahi Kasei Co., Ltd. product name "Tufden F3440", styrene content 35.5% by mass, vinyl content 40% by mass, weight average molecular weight 100 x 10 ⁴ , not applicable to component (A1), but component (A2) applies. Tg=-25℃
Unmodified SBR: Product name "HP755B" manufactured by JSR Corporation, solution polymerized styrene-butadiene copolymer, Tg = -18°C

Filler carbon black: Product name “#78” manufactured by Asahi Carbon Co., Ltd.
Silica 1: Product name "Nipsil (registered trademark) AQ" manufactured by Tosoh Silica Co., Ltd. CTAB 165, BET specific surface area 205
Silica 2: CTAB79 manufactured by Tosoh Silica

Other silane coupling agents: bis(3-triethoxysilylpropyl) disulfide, product name “Si75” manufactured by Evonik
C ₅ - C ₉ resin: Product name “Quinton (registered trademark) G100B” manufactured by Nippon Zeon Co., Ltd.
Zinc stearate: Sigma-Aldrich product number 307564
Antiaging agent (6PPD): N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, trade name "Nocrac 6C" manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
Vulcanization accelerator (1) (DPG): 1,3-diphenylguanidine, trade name "Soccinol (registered trademark) DG" manufactured by Sumitomo Chemical Co., Ltd.
Vulcanization accelerator (2) (MBTS): di(2-benzothiazolyl) persulfide, trade name “Noxela (registered trademark) DM-P” manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
Vulcanization accelerator (3) (CBS): N-cyclohexylbenzothiazole-2-sulfenamide, trade name “Noxela (registered trademark) CZ-G” manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.

The amount of bound styrene, the microstructure of the butadiene moiety, the molecular weight, the shrinkage factor (g'), the Mooney viscosity, Tg, the modification rate, the presence or absence of nitrogen atoms, and the presence or absence of silicon atoms of the modified conjugated diene polymer (A1) are as described above. Analyze by method.

<Synthesis of modified SBR (1)-component (A1)>
The internal volume is 10 L, the ratio of internal height (L) to diameter (D) (L/D) is 4.0, the inlet is at the bottom, the outlet is at the top, and it is a tank type reaction with a stirrer. The polymerization reactor is a tank-type pressure vessel equipped with a stirrer and a jacket for temperature control. 1,3-butadiene, from which water has been removed in advance, is mixed at 17.2 g/min, styrene at 10.5 g/min, and n-hexane at 145.3 g/min. In a static mixer installed in the middle of the piping that supplies this mixed solution to the inlet of the reaction group, n-butyllithium for inactivating residual impurities was added at a rate of 0.117 mmol/min and mixed, and then added to the bottom of the reaction group. Continuously supplied. Furthermore, 2,2-bis(2-oxolanyl)propane as a polar substance is mixed vigorously with a stirrer at a rate of 0.019 g/min, and n-butyllithium as a polymerization initiator is mixed at a rate of 0.242 mmol/min. It is supplied to the bottom of the polymerization reactor to continue the polymerization reaction continuously. The temperature is controlled so that the temperature of the polymerization solution at the top exit of the reactor is 75°C. When the polymerization was sufficiently stabilized, a small amount of the polymer solution before addition of the coupling agent was extracted from the top outlet of the reactor, and after adding an antioxidant (BHT) at 0.2 g per 100 g of polymer, the solvent was removed. The Mooney viscosity at 110°C and various molecular weights are measured. Next, tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine diluted to 2.74 mmol/L as a coupling agent was added to the polymer solution flowing out from the outlet of the reactor at a rate of 0.0302 mmol/min ( The polymer solution to which the coupling agent has been added is mixed by passing through a static mixer to undergo a coupling reaction. At this time, the time until the coupling agent was added to the polymerization solution flowing out from the outlet of the reactor was 4.8 minutes, and the temperature was 68°C, which is the same as the temperature during the polymerization process and the temperature before adding the modifier. The difference is 7°C. An antioxidant (BHT) is continuously added to the coupling-reacted polymer solution at a rate of 0.055 g/min (n-hexane solution) at a rate of 0.2 g per 100 g of polymer to terminate the coupling reaction. do. Simultaneously with the antioxidant, 10.0 g of oil (trade name "JOMO Process NC140" manufactured by JX Nippon Oil & Energy Corporation) is continuously added to 100 g of the polymer and mixed using a static mixer. The solvent is removed by steam stripping to obtain modified SBR (1) as component (A1).

When modified SBR (1) was analyzed by the above method, each value was as follows, and corresponds to component (A1).
Amount of bound styrene = 35% by mass,
Vinyl bond amount (1,2-bond amount) = 42 mol%,
Mw=85.2×10 ⁴ g/mol,
Mn=38.2×10 ⁴ g/mol,
Mw/Mn=2.23,
Peak top molecular weight (Mp ₁ )=96.8×10 ⁴ g/mol,
Peak top molecular weight ratio (Mp ₁ /Mp ₂ ) = 3.13,
Proportion of "specific high molecular weight component" = 4.6%,
Contraction factor (g') = 0.59,
Mooney viscosity (100°C) = 65,
Tg = -24°C, and denaturation rate = 80%.

Moreover, the modified SBR (1) has a nitrogen atom and a silicon atom.

Modified SBR (1) has a "degree of branching" of 8, which corresponds to the number of branches expected from the number of functional groups and the amount added of the coupling agent (which can also be confirmed from the value of the shrinkage factor), and one molecule of the coupling agent The "number of SiOR residues" corresponding to the value obtained by subtracting the number of SiORs reduced by the reaction from the total number of SiORs possessed is 4.

<Synthesis of modified SBR (2)-component (A2)>
A cyclohexane solution of 1,3-butadiene and a cyclohexane solution of styrene were added to a dry, nitrogen-purged 800 mL pressure-resistant glass container so that the total amount was 67.5 g of 1,3-butadiene and 7.5 g of styrene. - After adding 0.6 mmol of ditetrahydrofurylpropane and 0.8 mmol of n-butyllithium, polymerization is carried out at 50° C. for 1.5 hours. At this time, 0.72 mmol of [N,N-bis(trimethylsilyl)-(3-amino-1-propyl)](methyl)(diethoxy)silane was added to the polymerization reaction system where the polymerization conversion rate was approximately 100%. and perform a denaturation reaction at 50°C for 30 minutes. Thereafter, 2 mL of a 5% by mass solution of 2,6-di-t-butyl-p-cresol (BHT) in isopropanol is added to stop the reaction, and the mixture is dried according to a conventional method to obtain modified SBR. The microstructure of the modified SBR has a bonded styrene content of 10% by mass, a vinyl bond content of the butadiene moiety of 40%, and a peak molecular weight of 200,000. Further, Tg is -60°C.

<Preparation and evaluation of rubber composition>
In accordance with the formulations shown in Tables 1 and 2, rubber compositions were manufactured using a normal Banbury mixer for Example 1 and Comparative Example 1. For Examples 2 to 7 and Comparative Examples 2 to 5, rubber compositions were produced using a normal Banbury mixer. Further, a pneumatic radial tire for a passenger car having a size of 195/65R15 is produced using the rubber composition as a tread rubber. The rubber composition or tire is evaluated for wet performance, abrasion resistance, low rolling resistance, and fracture resistance by the following methods. Each evaluation is shown in Table 1.

The peak temperatures of the tan δ temperature dispersion curves of the polymer phase (1) and polymer phase (2) of each rubber composition, the filler proportion in the polymer phase (1), and the average aggregate area of the filler in the polymer phase (1) are as described above. Obtained using the method described above.

<Wet performance>
For Example 1 and Comparative Example 1, vulcanized rubber was made to fit a measurement jig with a major axis of 40 mm and a minor axis of 20 mm, and a load cell detected the frictional force generated when it was pressed against a fixed wet iron plate road surface and moved back and forth. Then, the coefficient of dynamic friction was calculated. Calculations are made for Examples 2 to 7 and Comparative Examples 2 to 5.

<Abrasion resistance>
After vulcanizing the rubber composition at 145°C for 33 minutes, the amount of wear is measured at 23°C using a Lambourn abrasion tester in accordance with JIS K 6264-2:2005. The value of the amount of wear is calculated by taking its reciprocal and is expressed as an index, with the value of Comparative Example 1 set as 100. The larger the index value, the smaller the amount of wear and the better the wear resistance.

<Low rolling resistance>
For Example 1 and Comparative Example 1, the index was calculated based on tan δ at 50°C. Examples 2 to 7 and Comparative Examples 2 to 5 are indexed. The smaller the index value, the lower the rolling resistance, and the better the rolling resistance.

<Destruction resistance properties>
For Example 1 and Comparative Example 1, the rubber compositions were subjected to a tensile test at room temperature in accordance with JIS-K6251, and the fracture stress of the vulcanized rubber composition was calculated from the obtained results. For Examples 2 to 7 and Comparative Examples 2 to 5, the rubber compositions were subjected to a tensile test at room temperature in accordance with JIS-K6251 to measure the breaking stress of the vulcanized rubber compositions. The value of Comparative Example 1 is set as 100, and each value is expressed as an index. The larger the index value, the better the fracture resistance.

As shown in Table 2, the rubber composition according to the present invention allows wet performance, abrasion resistance, low rolling resistance, and fracture resistance to be highly balanced.

According to the present invention, it is possible to provide a rubber composition that has a high balance of wet performance, abrasion resistance, low rolling resistance, and fracture resistance. According to the present invention, it is possible to provide a tire that has a high balance of wet performance, wear resistance, low rolling resistance, and fracture resistance.

Claims (5)

Contains a rubber component and a filler,
The rubber component includes at least a modified conjugated diene polymer (A1), a modified conjugated diene polymer (A2), and a third polymer, which are different from each other,
The modified conjugated diene polymer (A1) has a weight average molecular weight of 20×10 ⁴ to 300×10 ⁴ , and has a molecular weight of 200×10 ⁴ with respect to the total weight of the modified conjugated diene polymer (A1). It contains 0.25 to 30% by mass of the modified conjugated diene polymer having a molecular weight of ~500×10 ⁴ , and has a shrinkage factor (g') of less than 0.64,
The rubber component is separated into at least two polymer phases, a polymer phase (1) having the highest peak temperature of the tan δ temperature dispersion curve and a polymer phase (2) having the lowest peak temperature,
The polymer phase (1) and the polymer phase (2) are mutually incompatible,
The polymer phase (1) includes at least the modified conjugated diene polymer (A1), the modified conjugated diene polymer (A2), and the filler,
The polymer phase (2) contains natural rubber, synthetic isoprene rubber, or butadiene rubber with a cis-1,4 content of 90% by mass or more,
The modified conjugated diene polymer (A1) and the modified conjugated diene polymer (A2) are modified styrene-butadiene rubber,
The difference in glass transition temperature (Tg) between the modified conjugated diene polymer (A1) and the modified conjugated diene polymer (A2) is 20 to 40°C,
The third polymer is one selected from the group consisting of natural rubber, synthetic isoprene rubber, and butadiene rubber having a cis-1,4 content of 90% by mass or more,
The ratio (%) of the mass of the filler in the polymer phase (1) to the mass of the polymer present in the polymer phase (1) is X, the average aggregate area (nm ² ) of the filler in the polymer phase (1) When is Y, X and Y are expressed by the following formula (1):
Y<4.8X+1200 (1)
A rubber composition that satisfies the following. The rubber composition according to claim 1, wherein X in the formula (1) is larger than 100. According to claim 1 or 2, the total amount of the modified conjugated diene polymer (A1) and the modified conjugated diene polymer (A2) is 50 parts by mass or more with respect to 100 parts by mass of the rubber component. rubber composition. A tread rubber using the rubber composition according to any one of claims 1 to 3. A tire using the rubber composition according to any one of claims 1 to 3.